Cardiovascular disease frequently arises from the accumulation of atheromatous deposits on inner walls of vascular lumen, particularly the arterial lumen of the coronary and other vasculature, resulting in a condition known as atherosclerosis. These deposits can have widely varying properties, with some deposits being relatively soft and others being fibrous and/or calcified. In the latter case, the deposits are frequently referred to as plaque. These deposits can restrict blood flow, leading to myocardial infarction in more severe cases.
Fractional flow reserve (FFR) is a physiological measurement typically used to assess blood flow. FFR is determined by measuring the maximum myocardial flow in the presence of a stenosis (i.e., a narrowing of the blood vessel) divided by the normal maximum myocardial flow. This ratio is approximately equal to the mean hyperemic (i.e., dilated vessel) distal coronary pressure divided by the mean aortic pressure. Distal coronary pressure is usually measured with a pressure sensor mounted on the distal portion of a guidewire after administering a hyperemic agent into the blood vessel. Mean aortic pressure is measured using a variety of techniques in areas proximal of the stenosis, for example, in the aorta.
FFR provides a convenient, cost-effective way to assess the severity of coronary and peripheral lesions. FFR also provides an index of stenosis severity that allows rapid determination of whether an arterial blockage is significant enough to limit blood flow within the artery, thereby requiring treatment. The normal value of FFR is about 1.00. Values less than 0.80 are deemed significant and require treatment, which may include angioplasty and stenting.
Although FFR is useful in determining whether or not treatment is needed, current methods have yet to address the effectiveness of the provided treatment. As it is unknown whether or not the provided treatment has adequately resolved the issue, the patient may still face a long road to full recovery.